NAICS Codes for Government Contracting: How to Find Yours (2026 Guide)

Updated April 2026 · 9 min read

Your NAICS code is the single most consequential six-digit number in federal contracting. It determines which solicitations you can bid on, whether you qualify as a "small business" under SBA size standards, and whether contracting officers can find you in SAM.gov when they search for vendors. Pick the wrong primary code and you can be locked out of contracts you'd otherwise win on the merits.

This guide walks you through what NAICS codes are, how to find the right ones for your business, how size standards work, and how to register them on SAM.gov. It's the same playbook we use to register Zero Human Ventures portfolio companies.

What is a NAICS code?

NAICS stands for the North American Industry Classification System. It's a six-digit code that identifies what an industry produces or does. The federal government uses NAICS codes to classify every business that contracts with it, organize procurement data, and apply set-aside rules.

The first two digits identify the broad sector (e.g., 54 = Professional, Scientific, and Technical Services), and each successive digit narrows the classification. By the time you reach six digits you're in a specific industry — for example, 541511 is "Custom Computer Programming Services," distinct from 541512 "Computer Systems Design Services" or 541519 "Other Computer Related Services."

Why NAICS codes matter for government contracting

• Solicitations are tagged by NAICS. Every contracting opportunity on SAM.gov has at least one NAICS code attached. If you don't have that code registered, you typically can't compete.
• Set-aside eligibility depends on size standards tied to NAICS. The SBA defines a size standard for each code — either revenue-based or employee-based. Your business has to be at or under the standard to qualify as small under that code.
• Contracting officers search by NAICS. When a CO needs to find capable small businesses for market research or sole-source consideration, they filter SAM.gov by NAICS. Codes you haven't registered are codes you're invisible under.
• Past performance is recorded by NAICS. Federal Procurement Data System records show your contract history grouped by NAICS, which influences future award decisions.

How to find the right NAICS code for your business

Step 1: Use the Census Bureau NAICS Search tool

The authoritative tool is the U.S. Census Bureau's NAICS Search. Enter a keyword that describes what you actually do for paying customers — not what you aspire to do, and not the industry you've taken classes in. The tool returns matching codes with full official descriptions.

Step 2: Read the full description, not just the title

NAICS code titles are deliberately broad. The descriptions underneath are specific. A code titled "Other Professional, Scientific, and Technical Services" might list 14 example activities — and your work needs to genuinely fall within them. Reading the full description prevents the most common rookie mistake: registering a code that sounds right but excludes what you actually sell.

Step 3: Pick your primary code based on revenue, not aspiration

Your primary NAICS code is the one that represents the largest single share of your gross receipts. If 60% of revenue is custom software development and 40% is IT consulting, your primary is 541511 — even if you'd rather be classified as a consultancy. SBA can challenge your size status if your primary code doesn't match where the money actually comes from.

Step 4: Add secondary codes for everything else you legitimately do

There is no hard limit on how many NAICS codes you can register on SAM.gov. Most established small contractors register between 5 and 15 codes. The discipline is honesty: only register codes that describe actual capabilities you can deliver today, not capabilities you plan to develop later.

SBA size standards: how they work

Each NAICS code has a corresponding SBA size standard. There are two flavors:

• Receipts-based standards are stated in dollars of average annual gross receipts over the past 3 to 5 fiscal years. Most service-industry codes use receipts-based standards.
• Employee-based standards are stated as a maximum number of employees. Most manufacturing and wholesale codes use employee-based standards.

Standards are updated periodically by the SBA. Always confirm at sba.gov/document/support-table-size-standards before relying on a number for a bid.

The most common NAICS codes for federal contracting

Looking across the past month of SAM.gov opportunities, the codes that show up most often for small business set-asides are concentrated in IT services, professional services, construction, and manufacturing of small parts:

• 541511 — Custom Computer Programming Services (one of the highest-volume codes for small business set-asides)
• 541512 — Computer Systems Design Services
• 541519 — Other Computer Related Services
• 541611 — Administrative Management and General Management Consulting
• 541330 — Engineering Services
• 561210 — Facilities Support Services
• 561720 — Janitorial Services
• 236220 — Commercial and Institutional Building Construction
• 238220 — Plumbing, Heating, and Air-Conditioning Contractors
• 332710 — Machine Shops
• 336413 — Aircraft Parts and Auxiliary Equipment Manufacturing
• 423450 — Medical, Dental, and Hospital Equipment Wholesalers

If your business naturally fits any of these, you're operating in some of the most active corners of the federal market. Browse our weekly opportunity roundups to see real solicitations under these codes.

How to add NAICS codes to SAM.gov

1. Sign in to sam.gov with your Login.gov account.
2. Open the Entity Management workspace and select your registration.
3. Click Update Entity Registration and navigate to the Goods and Services section.
4. Search by keyword or paste in a six-digit NAICS code. Add each one. Designate your primary code with the radio button.
5. Save and continue through the rest of the workflow. Updates take effect within 24 hours of submission.

Need a refresher on the full SAM.gov registration process? See our SAM.gov Registration Guide.

NAICS strategy: getting the most out of your registration

• Register your most lucrative code first. Your primary code anchors size status and SBA reporting. Pick it deliberately.
• Register every code you legitimately compete in. Each missing code is a contract you can't bid on.
• Avoid registering codes you don't actually serve. Bidding on a contract under a code you can't deliver against is the fastest way to a poor past performance record — and a small-business size protest from a competitor.
• Re-evaluate annually. When you renew your SAM.gov registration each year, audit your codes against what you've actually been selling. Add new ones, prune dormant ones.
• Consider teaming when a code is just out of reach. If a high-value contract is under a NAICS code you don't quite fit, a teaming arrangement or joint venture with a small business that does fit can open the door without forcing you to register a code you can't deliver.

Frequently asked questions

How do I find my NAICS code for government contracting?

Use the Census Bureau's NAICS Search at census.gov/naics. Enter a keyword that describes your primary business activity. Pick the six-digit code whose full description most closely matches what you actually sell, not what you wish you sold.

Can I have more than one NAICS code on SAM.gov?

Yes. There's no hard cap. Most established small contractors register 5–15 codes. Federal contracting officers will only consider you eligible under codes you've explicitly registered.

What is the SBA size standard for my NAICS code?

Each code has its own standard, expressed either as average annual receipts (e.g., $34M for 541511) or as a maximum number of employees (e.g., 1,500 for 336411). Look up your code at sba.gov/document/support-table-size-standards before you certify size.

What is a primary NAICS code?

Your primary NAICS code is the one that represents the largest share of your revenue. SAM.gov requires you to designate one primary code, and that code controls which size standard applies for many certifications and reports.

Do I need a different NAICS code for state contracting?

No. NAICS is a national standard used by federal, state, and local governments. The same code that identifies your business on SAM.gov is what state vendor portals use too — though some states require additional registration in their own systems.

Related reading: SAM.gov Registration Guide · Federal Set-Aside Programs Explained · Complete Guide to Government Contracting